As long as you set it up right in the first place, water-cooling is very low maintenance, and minimal risk. It's when you start cutting corners and rushing that Bad Things start to happen.

The P182 isn't really a good case for watercooling; you're almost certainly going to have to hang the radiator on the back of the case. You might be able to attach a rad to the top fan, but I don't think there's enough clearance beneath the fan before it hits the motherboard.

As far as noise reduction goes, case airflow is still important, because not all the heat goes into the water for the radiator to handle, and you still need to carry away the heat coming off the minor motherboard components. Watercooling can potentially make your system quieter, but it's usually only at high overclocks/heatloads that it can be quieter than good aircooling. Even then, much of the quietness comes from using larger double and triple radiators, which usually have to be hung outside the case.

Honestly, you're going to have trouble cooling both your CPU and GPU for $200. I just tried making a shopping list for that amount, and I'm not sure it's actually possible. There's been a fairly significant price increase on watercooling stuff (among other things) the last week or so, which pretty much ruined any chance of pulling it off.

For your CPU alone, you could look at something like THIS, which is basically self-contained, performs well, costs $145 plus tax/s&h, and is a good way to introduce yourself to watercooling. It's only got a single-sized radiator though, so I wouldn't want to try adding the video card to it. You're probably looking at another $100 for the hardware to put the GPU in your loop, plus the cost of a larger radiator to properly handle the heat.